[ RADIOLOGY I

SPONDYLOLYSIS AND/OR SPONDYLOLISTHESIS:LET'S GET IT RIGHT AND STIR THINGS UPby Terry R. Yochum, D.C., D.A.C.B.R.

The topic of spondylolysis and/or spondylolisthesis hasbeen clouded with confusion for many years. To understandthe true etiology as a stress fracture rather than an inheritedcongenital anomaly or predisposition has been a lifelongquest for me. The normally developing pars interarticulares isa fully ossified structure at birth and without a local synchon-drosis to undergo nonunion. There has never been a patientborn with a lumbar spondylolysis and/or spondylolisthesis.The true etiology of spondylolysis (pars defects) is that ofa stress fracture, which is, in fact, a fatigue fracture whererepetitive stress on normal bone allows the bone to fatigue,much like you see in the metatarsal bones and tibia withmarathon runners and gymnasts.

To fully understand the concept of the pain-generatingfactors associated with spondylolysis and/or spondylolis-thesis, one must look beyond plain films and computedtomography to more physiological imaging. In the past, Ihave stressed the importance of determining the presence/

absence of increased physiological activity at the pars in-terarticularis as an aid to developing an accurate diagnosisand appropriate treatment plan for patients who have orare at risk for spondylolysis, coining the term "PENDINGSPONDYLOLYSIS" for those who have a developing stressfracture without frank separation. Historically, two modesof diagnostic imaging have been used to assess whetherphysiologic activity is present and associated with existingpars defects. Radionuclide bone scan imaging, particularlySPECT (Single Photon Emission Computed Tomography),has often been the examination of choice, however suffersfrom two drawbacks; it does expose the patient to ionizingradiation and it provides very little anatomical information.Fortunately, these concerns have been addressed with theadvent ofMR imaging.

Having reviewed thousands of cases, often with sportsrelated back pain and/or spondylolysis, I have had the op-portunity to see proven value ofMR imaging for evaluation

of the physiological activity that oc-curs adjacent to a pars defect, or thatwhich is hidden in the region of thepars interarticularis when the defect is,in fact, "PENDING". I feel, at thispoint in time, that SPECT imaging isprobably no longer the exam of choice,since there is so much more informa-tion obtained with the physiologicalimaging of magnetic resonance. Ad-ditionally, the exquisite anatomicalinformation that MR imaging providescan be invaluable in demonstratingother possible causes of back pain inthose individuals whose MR findingsare negative for spondylolysis. Theability to evaluate the spinal canal,exiting nerve roots and the integrityof the discs, along with the surround-ing paraspinal musculature, offers somuch more information in the evalua-tion of a young athlete with persistentback pain with what is often repetitivehyperextension.

14 I The American Chiropractor I JUNE 2010

Let's STIR Thin~s Up in the Evalu-ation of Spondylolysis and/or Spon-dylolisthesis

I have seen many cases where bonemarrow edema adjacent to the pars or

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hidden within an intact pars on its wayto becoming a pars defect (PE D-ING SPONDYLOLYSIS) has beenmissed on standard T2-weighted im-ages, where a STIR imaging sequenceclearly provides this information. Atthis point in time, I offer to the profes-sion that an MRI scan should be theexam of choice, with the proviso thatthe MR protocol includes a stronglyfluid sensitive pulse sequence, such asSTIR (short-tau inversion recovery) orother strong fat-suppression protocol.When appropriate clinical managementdepends on whether the spondylolysisand/or spondylol isthesis is active and/or inactive, only physiological activitywill provide that information. If yourlocal imaging center does not includeSTIR or other fat-suppressed (FatSat)pulse sequence as part of their routinelumbar MRI scan, requesting a sagittalSTIR imaging will definitively answerthe question of normal or increasedphysiological activity in the region ofthe pars interarticularis. When order-ing this additional study to the standardlumbar spine MRI scan, it will onlyadd a few minutes to the overall imag-ing time and should add no additionalexpense to the study.

Spondylolysis should be includedin the differential for any patient whocomplains of low back pain due torepetitive hyperextension, be it sportsor industrial related. Physical examfindings such as a positive Stork (singleleg hyperextension) test, often positivein acute facet syndrome and/or hot parsabnormality, may further indicate the

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need for more physiological imagingof the region of the lower lumbar parsinterarticularis. When repeating anMRI scan to evaluate whether the bonemarrow edema adjacent to the pars hassubsided and the patient can be removedfrom the standard Boston overlap bracethat the patient has been placed in, theonly imaging sequence really requiredto determine that the active pars defecthas become inactive is the sagittal STIRfluid-sensitive imaging sequence. Thisshould be performed after the patienthas been in a Boston overlap brace fora minimum of three to four months and,if the imaging study shows no evidenceof persistent edema, one can allowthe patient to slowly go back to theirsports or work related physical activi-ties. Core stabilization exercises andphysical activity back to their normalroutines should occur slowly, and somecommon sense should be used by theclinician in not allowing the athlete togo back at full performance too quickly.For a more detailed discussion of thiscondition, see Chapter 5 of the newedition of Essentials of Skeletal Radi-ology, published in 2005 by LippincottWilliams & Wilkins. Included thereare some positive treatment protocolsfor patients with active spondylolysisand/or spondylolisthesis.

As a final comment, it is always ap-propriate and very useful to the radiolo-gist for the referring clinician to clearlystate on the imaging request form theworking diagnosis. Tell the radiolo-gist why imaging is being performedand what questions you are trying to

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answer. This is particularly important in the evaluation ofspondylolysis, so that right imaging sequences are performedand the sometimes subtle changes in marrow signal are notoverlooked. Including a copy of the material in Chapter5 of my textbook covering "Active versus Inactive Spon-dylolisthesis" and perhaps a copy of the article which I havereferenced in this text along with your imaging request mayalso be useful for emphasis. The additional information mayhelp the medical radiologist to provide you the right reportand ensure proper and complete evaluation of the patient'spresenting complaint.

Thanks to Dr. Jeff Thompson, Professor and Chairman,Department of Radiology, Texas Chiropractic College,Houston, Texas, for his help in preparation of the text andimages for this article.

Dr. Terry R. Yochum is a second generation chiroprac-tor and a Cum Laude Graduate of National College ofChiropractic, where he subsequently completed his ra-diology residency. He is currently Director of the RockyMountain Chiropractic Radiological Center in Denver,Colorado, and Adjunct Professor of Radiology at the Southern Califor-nia University of Health Sciences, as well as an instructor of skeletalradiology at the University of Colorado Schoolof Medicine, Denver,Co. Dr. Yochum can be reached at J -303-940-9400 or bye-mail atdcrad099@aol.com.ReferencesI. Yochum, TR, Rowe, LJ: Essentials of Skeletal Radiology, 3rd ed.,

Chapter 5,Williams & Wilkins, Baltimore, Maryland, 2005

2. Yochum, T.R., et al., Active or Lnactive Spondylolysis and/or Spondylolis-thesis: What's the Real Cause of Back Pain? J.N.MS: Journal of theNeuromusculoskeletal System, Vol. 10, No.2, Summer 2002.111I